In recent years, for example, HDMI (High Definition Multimedia Interface) has come into widespread use as a communication interface for transmitting digital video signals, i.e., uncompressed (baseband) video signals (hereafter, referred to as “image data” as appropriate) and digital audio signals (hereafter, referred to as “audio data” as appropriate) along with the video signal thereof from a DVD (Digital Versatile Disc) recorder, a set top box, or another AV source (Audio Visual source) to a television receiver, a projector, or another display, at high speed. For example, description has been made in Patent Document 1 regarding the details of the HDMI standard.    Patent Document 1: WO 2002/078336